The packing and shipping container art is one of the most highly developed arts, and even the fabrication of such containers from moldable foamed plastics, such as expandable polystyrene foam and the like, has already received wide acceptance. It is significant to note, however, that the use of foamed plastics has leaned heavily toward container liners or complete containers which are encased in an outer, protective container; with only limited use of the foamed plastic as the sole packing and shipping container.
A search of the patent art concerning foamed plastic containers suitable for use as sole packing and shipping containers has brought to light the following U.S. patents as most closely related to the novel structures disclosed and claimed herein.
a. J. M. Harrison U.S. Pat. No. 3,156,371 PA1 b. R. O. Ragan et al U.S. Pat. No. 3,317,114 PA1 c. R. A. Bellamy U.S. Pat. No. 3,330,437 PA1 d. D. L. Brink U.S. Pat. No. 3,675,808 PA1 e. J. L. Wilgus U.S. Pat. No. 4,010,865
The Harrison container leaves much to be desired due to difficulty in handling the loosely joined panels of the knockdown configuration and the absence of joining means for the side panels prior to interengagement with the top.
The Ragan et al container inherently relates to a thin-walled structure, hardly suitable as a sole shipping container, and it is assembled by a heat sealing process which makes on site assembly of containers at the point of use impractical.
The Bellamy container is impractical as a sole shipping container because of its many external irregularities, and the structure disclosed does not permit flat stacking in extended configuration.
The Brink patent relates particularly to a fruit packing container in which the lid is completely removable to permit the open container to be used for the display and dispensing of fruit. The structure therefore does not lend itself to general purpose, sole shipping containers.
The Wilgus patent relates to a container in which foamed plastic panels are held together by an outer skin of tough abrasion-resistant material; and such a composite construction inherently adds to cost and construction problems as compared with a container which can be completely molded from foamed plastic material.
In addition to the above mentioned patent art, it should be noted that foamed plastic containers are available on the market in which the six walls forming a complete container are molded as a single blank in a manner to be stackable to any convenient height when in the extended knock-down configuration and in which the sidewalls interlock, as raised to the vertical position to permit arrangement of goods within a formed container which is further locked together by hinged closing of a lid panel integral with one of the sidewalls.
In order that the examiner may visualize this commercially available construction, and to provide a point of reference concerning improvements of the present invention, such commercially available container has been illustrated in FIGS. 1 and 2 of the drawing.
While this commercially available container is neat and practical as a sole shipping container, and reasonably strong and durable when sealed by tape or strapping in the conventional way, it presents problems in the bulk handling which shipping containers frequently encounter, in which several layers of containers may be loaded on a pallet and loaded pallets stacked several tiers high. In such practices, the lower containers on a loaded pallet and all containers on pallets having other pallets stacked above them must withstand a substantial compressive force; and it is in this area that the commercially available foamed plastic containers leave much to be desired.